Usually decorative sheets have been made using by the following processes: (a) a resin film is formed on a paper surface by coating a polyvinyl chloride resin sol on the paper surface, (b) a vinyl chloride sheet as a backing is subjected to printing, embossing, or other working, (c) a foaming agent is used to produce a three dimensional appearance, or (d) flake-like or pellet-like chips are sprayed and adhered at random in order to provide a stereoscopic appearance. See, for example, Interior Encyclopedia published by the Trade Association for Wall-Covering Materials of Tokyo, Japan in 1988 at pages 697 and 698.
If a stereoscopic texture called "hammer tone" (i.e., as if hammered at random to form a three dimensional or other stereoscopic appearance) is attempted to be produced by the printing or embossing processes as described above, a poor stereoscopic appearance results because the same pattern appears repeatedly according to the circumference of the printing roll or embossing roll. No random texture is formed.
If a foaming agent is used, the expression of stereoscopic appearance is reduced. If a decorative sheet is adhered using chips, flaking of the chips is troublesome.
Usually in order to obtain a hammer tone texture, paint containing silicone resin is used. Japanese Unexamined Patent Publication (Kokai) No. 63-91168 discloses a coating composition containing a powdered silicone resin to form a hammer tone texture to form on a painted surface. Such a coating composition causes a hammer tone texture to appear because the silicone resin repels the coating composition components on the surface of the coating composition due to the low surface tension of the silicone resin. This is a non-wetting phenomenon. However, since a silicone resin has a low surface tension and is poor in compatibility with other coating composition components, it must be constantly immersed in a solvent. Thus, it has been difficult to coat a silicone resin by a method substantially other than spray coating.
However, application by spray coating has involved the following problems or restrictions:
(a) Thick application or uniform coating is difficult. PA1 When spray coating is conducted in a vertical direction, a problem of so-called "sagging" of the coating often occurs. PA1 (c) Since the capacity of a spraying can is limited, it is difficult to effect spray coating over a large area at one time without refilling or using a new spraying can. PA1 (d) In spray coating, very accurate viscosity adjustment is required to prevent clogging at the nozzle portion. A diluent or injection gas become indispensable for use in spraying. PA1 (e) After coating,, the coated object must be dried under for about 6 hours without heat or under strict drying conditions of about 180.degree. C. and about 20 minutes if crosslinking of coating is required. PA1 (a) to form a hammer tone texture exhibiting stereoscopic appearance free from repetition of the same pattern, PA1 (b) to easily form a decorative layer having a uniform and large area hammer tone texture, PA1 (c) that very accurate viscosity adjustment is unnecessary, that neither diluent nor injection gas is necessary, and that production cost is low. PA1 (d) that the drying temperature for hammer tone coating composition is lower than that used for spraying techniques.
Accordingly, it has been difficult to use the conventional silicone resin coating composition as decorative film, especially a decorative film that can be stored on a roll.